Abstract. Dual carbon isotope analysis of marine aerosol samples has been performed
for the first time demonstrating a potential in organic matter apportionment
between three principal sources: marine, terrestrial (non-fossil) and fossil
fuel due to unique isotopic signatures. The results presented here,
utilising combinations of dual carbon isotope analysis, provides conclusive
evidence of a dominant biogenic organic fraction to organic aerosol over
biologically active oceans. In particular, the NE Atlantic, which is also
subjected to notable anthropogenic influences via pollution transport
processes, was found to contain 80 % organic aerosol matter of biogenic
origin directly linked to plankton emissions. The remaining carbonaceous
aerosol was of terrestrial origin. By contrast, for polluted air advected
out from Europe into the NE Atlantic, the source apportionment is 30 %
marine biogenic, 40 % fossil fuel, and 30 % continental non-fossil fuel.
The dominant marine organic aerosol source in the atmosphere has significant
implications for climate change feedback processes.